The present invention relates to a screwholder for a screwdriver, and more particularly, to a low cost and reliable screwholder for a screwdriver.
As screwdrivers have been developed over the years, efforts have also been underway in developing various types of devices for holding a screw in cooperating engagement with the screw engaging/driving or tip end of a screwdriver. For example, in the early 1900's, several types of screwholders for screwdrivers were developed as represented by U.S. Pat. Nos. 864,633 (1907); 951,526 (1910); and 1,212,743 (1917). Each of these patents disclose spring urged gripping fingers where an exposed coil spring surrounds a screwdriver shank and functions to urge a pair of screw gripping fingers into gripping engagement with a screw adjacent the screw engaging/driving or tip end of a screwdriver. There are other examples in the prior art where an outer housing protectively surrounds a coil spring operating to urge screw gripping fingers of a screwholder into gripping engagement with the screw. Examples of such screwholder devices include U.S. Pat. No. 1,641,307 which employs a hexagonally shaped enclosed outer housing and U.S. Pat. No. 2,633,168 where a cylindrically shaped enclosed outer housing as disclosed. At the same time, it has been found desirable to provide a thumb disk or shoulder adjacent the screwdriver handle to operate the screwholder device. Examples of thumb disk/shoulder operative screwholder devices are shown, for example, in U.S. Pat. Nos. 2,762,408 and 2,933,114.
While each of the aforementioned and other prior art screwholder devices provide some of the features desirable in a preferred screwholder device, it is apparent that such prior art devices have not fully met market demands. In this connection, it has been determined from market studies that a screwholder with the following functional and structural features would be most desirable:
1. Single handed screwholder operation.
2. Thumb operation of the screwholder device.
3. Expanding/retracting screw gripping fingers associated with the screwholder.
4. Reduced screwholder components using standard parts where possible.
5. Improved manufacturability and assembly of screwholders.
6. Improved screwholder reliability during repeated use.
The screwholder device of the present invention has been developed with the foregoing design criteria in mind, as will become apparent from the description that follows.